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Thread: Ask David and Farrar: Technical Questions and Advice About Carbureting a DeLorean

  1. #11
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    My VIN:    16510 and carbureted

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    Quote Originally Posted by Michael View Post
    The engine cover looks extremely bowed up in the center, is that due to the air cleaner clearance? I saw one that had a hole cut out in the cover for that very reason, looked good and no doubt gave it a cooler intake charge.
    The engine cover is bowed because it's 30 years old. One day i will install some sort or bracket to give it extra support


    My fuel system has plenty of clearance. The engine cover was in the same condition when I was running K-jet.

  2. #12
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    Questions about carbing

    Hello, I'd like to know the intake port sizes, volume of port as well as the same dimensions on the stock CIS manifold runners would be nice too, and exhaust port sizes of the stock PRV.

    My plan, two threes and multiply crossed over 3 into 1 headers....... just looking to fully optimize what is there while I acquire heads and other bits to get serious about finding all the HP and torque the stock bumpstick can accommodate.

    It sure seems to me that there must be an easy 25 horses to be had over the stock configuration, if not 40.

    If this trail has already been blazed, in whole or in part, I'd be quite appreciative of any knowledge you can share.

    I also plan to fully control a higher output ignition's timing curve.


    BTW... my factory manual seemingly fails to specify the connecting rod length. Scaling the line drawing seems to indicate nearly 2:1. Could I also get confirmation on the connecting rod length? Thanks for any help you can offer.
    Last edited by EarlHickey; 05-02-2012 at 07:37 PM.

  3. #13
    Admins Never Retire Ron's Avatar
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    Quote Originally Posted by EarlHickey View Post
    BTW... my factory manual seemingly fails to specify the connecting rod length. Scaling the line drawing seems to indicate nearly 2:1. Could I also get confirmation on the connecting rod length? Thanks for any help you can offer.
    Here ya go (page 9):
    http://dl.dropbox.com/u/13720563/DeL..._21-Hybrid.pdf

  4. #14
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    Thank you for the info and that is a much nicer manual than the Delorean Workshop manual. Assuming the Volvo engine has the same connecting rod length, 2:1 it is.

    I noted that the Volvo pistons are shown with slight popups whereas the factory Delorean manual seems to illustrate dished pistons for it's 8.8:1 CR. If the Delorean uses dished pistons, do you know the volume of the dish? If it uses popups, do you know it's negative volume?

    Is the Delorean PRV the same as the Volvo B28?


    However, I'm still seeking port dimensions and volume if anyone knows. I'd prefer to do my homework, make sure I have all needed materials on hand and be ready to fab prior to taking it apart and having it inoperative.


    I don't think this one will need very large carbs. I also looked at a available header for the Delorean. My first impression was that the primaries were too large and short for a 6500 rpm redline engine that peaks under 6000 rpm. I'm a bit more inclined to believe this now that I know the internal geometry for sure. I just showed the Crabman and he seems to also agree.

    I really want excellent BSFC numbers along with my fatter torque band and more horsepower. I hate not getting every last bang for each drop of dino juice.

    Quote Originally Posted by Ron View Post

  5. #15
    Admins Never Retire Ron's Avatar
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    Quote Originally Posted by EarlHickey View Post
    Thank you for the info and that is a much nicer manual than the Delorean Workshop manual. Assuming the Volvo engine has the same connecting rod length, 2:1 it is.

    I noted that the Volvo pistons are shown with slight popups whereas the factory Delorean manual seems to illustrate dished pistons for it's 8.8:1 CR. If the Delorean uses dished pistons, do you know the volume of the dish? If it uses popups, do you know it's negative volume?

    Is the Delorean PRV the same as the Volvo B28?


    However, I'm still seeking port dimensions and volume if anyone knows. I'd prefer to do my homework, make sure I have all needed materials on hand and be ready to fab prior to taking it apart and having it inoperative.


    I don't think this one will need very large carbs. I also looked at a available header for the Delorean. My first impression was that the primaries were too large and short for a 6500 rpm redline engine that peaks under 6000 rpm. I'm a bit more inclined to believe this now that I know the internal geometry for sure. I just showed the Crabman and he seems to also agree.

    I really want excellent BSFC numbers along with my fatter torque band and more horsepower. I hate not getting every last bang for each drop of dino juice.
    The DeLorean uses a B28F.
    Sorry I don't know the details at that level for the engine (My head is full of US muscle cars ;-) but there are several here that do...hopefully someone will chime in.

    FWIW- I like your approach (homework, probing, questioning, ...) and suggest that if you are not going to keep the K-Jet fuel system, check out the EFI threads here -- At least throw the idea in your bag of ideas, and shake it up, before you choose ;-)

    EDIT: You may want to start your own project thread
    Last edited by Ron; 05-03-2012 at 09:18 AM.

  6. #16
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    Thank you again for your help and your suggestions are noted!

    The choice has already been made for me, the car is already with one lonely carburetor that does not please my eye or seat of the pants internal dyno.

    I've been told many times I should have a stainless car since I specialize in the white metals and have built several largely stainless and ti motorcycles. I build them to go fast and it would seem that I prefer starting with mules wearing flip flops as opposed to thoroughbreds in nikes. Most likely it's really a case of starting with what is affordable and on hand.

    It would seem the planets were in proper alignment for me to be honored with Delorean ownership and I'm happy with what I got even though several aspects of it could better. It's perfect for my purposes.

    I'm quite competent with the various forms of Bosch FI, especially CIS, as one of my daily drivers is a tweaked 245 that will do 130mph and change, returns 35 mpg at 80mph and will rev to just a tick south of 8,000 rpm. However, I did not get all the CIS system and I'm certain I will make this dog hunt without it.


    I think I'll start a general engine constraints thread and maybe see if many or all of the basic tuning dimensions can be gathered into one place for future tuners. If I find them on any of the various Volvo forums (which seems highly likely) I'll bring them here.

    It would be interesting to know the primary and collector dimensions of the currently offered headers available.

    An aside, I noticed Lingfelter has a DMC-12 featured on his site. I haven't spoken to him or worked with him in years. The last time was in the early 90's screwing together some of his fine components to make a 215 mph Vette. I wonder if he's graced a Delorean with his very masterful brilliance. Do you know? I don't see anything on the net that indicates he's done a Delorean supercar yet. I have him on my list of people to call this week.


    btw.... where is the registry so I can check into this car's history? I surely have no desire to type any factual info that may offend anyone.

    Do you have any recommendations for Volvo sites which seem inhabited with any land speed racers or other types of serious gear heads?

  7. #17
    Voice For Hire Farrar's Avatar
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    If you're really into engine modding, I'd suggest looking up the specs for the B28E engine. Compression ratio was 9.5:1 if I recall correctly. If you can get the specs for that camshaft profile, valve size and porting, you will have a really nicely-breathing PRV which can suck up as much fuel as your jets will provide.
    DeLorean status: test driving new engine

    "Our doubts are traitors,
    And make us lose the good we oft might win
    By fearing to attempt."
    -Wm. Shakespeare, Measure for Measure

  8. #18
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    Quote Originally Posted by Farrar View Post
    If you're really into engine modding, I'd suggest looking up the specs for the B28E engine. Compression ratio was 9.5:1 if I recall correctly. If you can get the specs for that camshaft profile, valve size and porting, you will have a really nicely-breathing PRV which can suck up as much fuel as your jets will provide.
    Thanks!

    Does the stock DMC engine use domed or dished pistons? I really can't tell from the Factory Service manual although they do look to be drawn as dished while the Volvo B27/28 manual shows domes. I'm not sure if their illustration may have likely been of one of the 10:1 engines listed in the same manual.

    I like the idea of smaller ports, valves and induction for this particular engine, does the B28E have larger ports and valves?

    Any hard numbers are appreciated, I'll root them out one way or the other.

    My preliminary studies have had me thinking if I were going to get very serious, warming up a later 90's 24V would be a smart move. I'm sure I could be wrong and some other variant of this engine may be better. I'm content, for now, with the stocker.


    Would you think the same header would work well on both the odd fire and split pin versions of this engine? I personally don't think so.

  9. #19
    Voice For Hire Farrar's Avatar
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    I have never taken one of these engines apart, but I have sent you the e-mail address of someone who has. He should be able to answer all of your questions, or point you to the appropriate literature.

    By the way, the 24v version is hard to find in the U.S., but here's hoping you get lucky. FYI, the camshaft is fitted from the other end, so if you plan on installing different camshafts in the 24v PRV, do it before the engine is in the car.

    Edit: Have you started a new thread about building up the engine? This thread is for carburetor questions, and there are people on here more knowledgeable about the engine in general than David and I are who may be able to help you out, but they won't be watching this space since it is in the carburetor subsection and most carb users haven't modded the engine in the ways that you are talking about.
    Last edited by Farrar; 05-03-2012 at 06:12 PM. Reason: ...Bill.
    DeLorean status: test driving new engine

    "Our doubts are traitors,
    And make us lose the good we oft might win
    By fearing to attempt."
    -Wm. Shakespeare, Measure for Measure

  10. #20
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    Thank you very kindly, sir!

    I'm not doing the engine thing yet, I've too many already apart in my shop and I like the engine in this one just fine!

    Have you any thoughts on a smooth bore butter fly carb minimum diameter to make 180 horsepower, using IR and six throats?

    Do you know if the stock runners will flow enough to make 180 horsepower?

    I think they just might and I'd like to know the maximum they are able to flow, without being touched.


    I noticed a plenum with runners cast integral on ebay that looks very much different than what came on mine.

    http://www.ebay.com/itm/160793546372...WAX:IT&vxp=mtr



    Mine does not look like this. Do two styles exist? Could you point me to a picture of the other style if so and when where they changed?

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